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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script lang="javascript" type="text/javascript" src="js/0307.js"></script>
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<body>
    <!-- <form method="post">
        <input type="text" id="t1"><br>
        <input type="text" id="t3"><br>
        <input type="button" value="+" onclick="myfun1();">
        <input type="button" value="-" onclick="myfun2();">
        <input type="button" value="*" onclick="myfun3();">
        <input type="button" value="/" onclick="myfun4();"><br>
        <input type="text" id="t2" readonly /><br>
    </form> -->



    <form method="post">
        <input type="text" id="t1"><br>
        <input type="text" id="t3"><br>
        <input type="button" value="+" onclick="myfun1(1);">
        <input type="button" value="-" onclick="myfun1(2);">
        <input type="button" value="*" onclick="myfun1(3);">
        <input type="button" value="/" onclick="myfun1(4);"><br>
        <input type="text" id="t2" readonly /><br>
    </form>
</body>
</html>